A space capsule returning solar particles to Earth crashed in the Utah desert after its parachute failed to open, but scientists were hoping that the star dust inside might have been saved.

A Hollywood stunt pilot was supposed to snag the Genesis capsule as it floated toward Earth on a parachute at the end of its three-year mission to collect solar ions.

But the capsule's parachutes didn't open, and the spacecraft tumbled out of control. It struck the ground at 310 kilometres per hour, six minutes after entering Earth's atmosphere.

The flight had gone smoothly until moments before impact, which left the 200 kilogram capsule half buried in the sand about 50 kilometres from the U.S. Army's Dugway Proving Ground, where the Genesis team watched a live broadcast of the events.

"Certainly now we are in a situation where the scientists ... are going to have to deal with a lot more contamination than they were hoping for," Genesis project manager Don Sweetnam said shortly after the crash.

Dr Charles Elachi, director of NASA's Jet Propulsion Laboratory in Pasadena, California, where the mission was based, said he was "still hopeful".

"All the data is there," Elachi said. "The question is: 'How contaminated is it?' It will make it much harder to analyse."

Blowing in the wind

The spacecraft collected ions that had been blown by solar winds on wafers of silicon, diamond, sapphire, gold and other materials in what scientists described as a 'fossil record' of the Sun.

It was the first extraterrestrial matter to be returned to Earth by a spacecraft since the U.S. Apollo and Soviet Luna missions brought back moon rocks in the 1970s.

Scientists hoped studying the materials would yield insights about the early formation of planets and the dawn of the solar system.

An initial check of the spacecraft showed that several pyrotechnic devices failed to fire and deploy the chutes. But the reason for the multiple failures was unclear, said Andrew Dantzler, NASA solar system division director.

The capsule and the canister inside were cracked, but scientists couldn't catalogue the damage to the samples because of the safety risks posed by the unexploded ordnance and gases emitted by the craft's batteries, he said.

A team of scientists and engineers headed to the crash site to assess the spacecraft and dig it out of its impact crater, Bob Corwin, recovery operations chief for Lockheed-Martin, said.

The team must also decide whether to crack open the capsule and retrieve the canister separately or leave it intact and ferry it via helicopter to a clean room at Michael Army Air Field.

"We're sorry we didn't get to perform the mid-air retrieval we trained so hard to perform, but our hearts really go out to the science team who is going to have a tougher job," Roy Haggard, director of flight operations, said.